There is not much to worry about in Penticton. The streets are generally safe after dark and the huge amount of tourists on the streets ensures you are never alone. The biggest safety issue may be the occasional bar brawl that occurs when the clubs close. Make sure you do not get involved or you will end up spending the night in jail.
If you are hiking or biking in the surrounding hills be aware the area is home to rattlesnakes and bears. The snakes, easily detected by their distinctive rattle, do not attack humans unless you enter their space and/or startle them -- such as abruptly walking into one along a trail. If you hear the rattle, understand it as a warning and keep your distance; the snake's bite can be fatal. Similarly, black bears inhabit the region surrounding Penticton and are happy to avoid humans unless surprised, cornered, and/or their cubs are threatened. Bear attacks are extremely rare but if you spot a bear in the area, it is best to steer clear. Cougars are being spotted by the locals more